The present invention is directed to a tissue graft construct comprising a matrix composition seeded with endothelial cells and at least one additional preselected, exogenous cell population for use in the repair of damaged or diseased tissues. The matrix composition for use in accordance with the present invention is selected from the group consisting of liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources. The matrix composition preferably comprises highly conserved collagens, glycoproteins, proteoglycans, and glycosaminoglycans. The matrix composition for use in this invention is derived from the tissue of a warm-blooded vertebrate.
The tissue graft constructs prepared in accordance with the present invention are substantially acellular matrices that provide a superior cell growth substrate resembling the matrix environment found in vivo. The natural composition and configuration of the matrix composition provides a unique cell growth substrate that promotes the attachment and proliferation of cells in vitro and induces tissue remodeling when the graft constructs are implanted in vivo.
As tissue graft materials, liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources, induce the growth of endogenous tissues upon implantation into a host (i.e., the graft materials induce remodeling). When used in such an application the tissue graft constructs appear not only to serve as a matrix for the growth or regrowth of the tissues replaced by the graft constructs, but also to promote or to induce such growth or regrowth of endogenous tissue. These graft materials can be used in an implantable sheet form or in injectable fluidized or gel forms for inducing the regrowth of endogenous tissues.
The present invention is directed to tissue graft constructs comprising a matrix composition selected from the group consisting of liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources, and further including added endothelial cells and at least one additional preselected, exogenous population of cells. The invention is also directed to methods of enhancing the vascularization of a tissue graft construct in vivo. The vascularization enhanced tissue graft constructs are prepared by seeding the matrix composition in vitro with endothelial cells or endothelial cell precursors (e.g., progenitor cells or stem cells) and at least one additional preselected or predetermined cell type prior to implanting or injecting the tissue graft construct into the host.
One embodiment provides a tissue graft construct for use in repairing diseased or damaged tissues. The tissue graft construct comprises a matrix composition selected from the group consisting of liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources, added endothelial cells, and at least one additional preselected, exogenous population of cells.
In another embodiment a vascularized tissue graft construct is provided for use in repairing diseased or damaged tissues. The tissue graft construct comprises a matrix composition selected from the group consisting of liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources, added endothelial cells, and at least one additional preselected, exogenous population of cells wherein the endothelial cells have been cultured on the matrix composition for a time sufficient to form vessels or vessel-like structures in vitro.
In another embodiment a method is provided for enhancing the vascularization in vivo of a tissue graft construct. The method comprises the steps of seeding in vitro a matrix composition selected from the group consisting of liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources, with a population of endothelial cells and at least one additional preselected, exogenous population of cells to form the graft construct, and implanting the graft construct into a vertebrate at a site in need of repair.
In yet another embodiment a method is provided for enhancing the vascularization in vivo of a tissue graft construct. The method comprises the steps of seeding in vitro a matrix composition selected from the group consisting of liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources, with a population of endothelial cells and at least one additional preselected, exogenous population of cells, culturing in vitro the endothelial cells for a time sufficient to induce the formation of vessels or vessel-like structures or components, and implanting the graft construct into a vertebrate in a site in need of repair.
In either of these method embodiments the matrix composition can be seeded with the additional preselected population of cells after the matrix composition is seeded with the endothelial cells, the matrix composition can be seeded with the additional preselected population of cells before the matrix composition is seeded with the endothelial cells, or the matrix composition can be seeded with the endothelial cells and the additional preselected population of cells simultaneously or nearly simultaneously.
The endothelial cells can be cultured in vitro on the matrix composition for a time sufficient to induce the formation of vessels or vessel-like structures, or the endothelial cells can be cultured on the matrix composition for a time sufficient to expand the endothelial cells (i.e., allow the endothelial cells to divide at least one time) without forming vessels or vessel-like structures in vitro. Alternatively, the graft construct can be implanted without expanding the endothelial cells. In any of these embodiments the additional preselected population of cells may or may not be expanded (i.e., allowed to progress through at least one cell division cycle) prior to implanting the graft construct.
In still another embodiment a method is provided of preparing a tissue graft construct for use in repairing diseased or damaged tissues. The method comprises the step of seeding in vitro a matrix composition selected from the group consisting of liver basement membrane and extracts and hydrolysates thereof, and processed collagen from vertebrate non-submucosal sources, with a population of endothelial cells, and at least one additional preselected, exogenous population of cells to form the graft construct. The method can further comprise the step of culturing the endothelial cells in vitro on the matrix composition for a time sufficient to induce the formation of vessels or vessel-like structures.
In any of these embodiments the at least one additional cell population can comprise a population of non-keratinized or keratinized epithelial cells or a population of mesodermally derived cells selected from the group consisting of fibroblasts, smooth muscle cells, skeletal muscle cells, cardiac muscle cells, multi-potential progenitor cells (e.g., stem cells), pericytes, and osteogenic cells. In various embodiments, the matrix composition can be seeded with endothelial cells and one or more of these additional cell types (i.e., the matrix composition can be seeded with endothelial cells and one, two, three, etc. of these additional cell types).